Process and device for the production of a yarn in an open-end spinning device

ABSTRACT

A spinning rotor  30  of an open-end spinning device  3  is slowed down for piecing to a low rotational piecing speed and is then accelerated to the operating speed. For this purpose the spinning rotor  30  or an element in drive connection with it is presented from a service unit  2  a drive transmission device  7  by means of which the spinning rotor  30  can be switched from normal production speed to a reduced piecing speed and back. In this process the drive transmission device  7  can be driven either by a driving apparatus  20  installed on the service unit  2  or by a drive belt  12  extending alongside the rotor spinning machine  1 . The driving apparatus  20  mounted on the service unit  2  is connected for control to a control device  5  for the control of the evolution of the rotational speed of the spinning rotor  30  which is driven according to a rotational speed course controlled by means of a program applied by the control device  5  during the time when its rotational speed deviates from its operating speed.

[0001] The present invention relates to a process according to the introductory clause of claim 1 as well as to a device to carry out this process.

[0002] With the high operating speeds of the spinning rotor that are in general use today, piecing under operational conditions cannot be carried out or can be carried out only with difficulty, and the piecing joint produced does not meet the necessary requirements. For this reason piecing takes place as a rule at a low rotational piecing speed of the spinning rotor, whereby the feeding and the drawing off of the pieced yarn from the spinning rotor is adapted to the rotational speed of the spinning rotor which runs up again at the latest after the piecing process (DE 2360296 A1)

[0003] It is furthermore a known method to maintain the rotational speed of the spinning rotor within a predetermined range of rotational speeds during the piecing process, and for this purpose a brake is assigned to the spinning rotor to be brought to bear upon the spinning rotor or to release it in function of the measured rotational speed behavior of the spinning rotor (DE 44 03 120 A1). However, only an approximate influence can be exerted upon the rotor speed, since a change in brake application can be undertaken only as a consequence of an ascertained deviation from the rotational speed, so that fluctuation of the spinning rotor's actual rotational speed around the predetermined target speed cannot be avoided.

[0004] It is the object of the present invention to create a possibility to control the rotor speed in a desired manner not only during the piecing process but also during the time when the rotor speed deviates from its operational speed.

[0005] The above-mentioned object is attained according to the invention through the characteristics of claim 1. By providing a drive transmission device, it is possible to drive the spinning rotor in a precise manner at a desired rotational speed or following a desired evolution of rotational speeds during the piecing process when the spinning rotor does not rotate at its operating speed.

[0006] The drive transmission device can then remain in use until the operating speed of the spinning rotor has been reached. It is however also possible to deactivate it earlier, when a controlled evolution of the spinning rotor speed has been achieved through other measures.

[0007] For the drive transmission device according to claim 2, a driving apparatus is preferably installed on the service unit so that such a driving apparatus need not be provided separately for every open-end spinning device. The solution according to the invention is thus economical from the point of view of material requirements as well as space requirement. Thanks to the direct control of the rotational rotor speed, a very precise evolution of the rotational rotor speed is achieved.

[0008] The rotational speed of the spinning rotor is advantageously controlled according to claim 3 during the piecing process. This type of control of the rotational rotor speed makes it possible to maintain this rotational speed for the piecing process at a rotational speed level or within a rotational speed range such as to lead to optimal results with respect to the piecing joint produced.

[0009] It is advantageous for the running up of the spinning rotor to its operating speed to take place according to claim 4 in coordination with the fiber feeding to the spinning rotor and/or the drawing off of the spun yarn from the spinning rotor. For this it can be a distinct advantage if, according to claim 5, it were not the spinning rotor but e.g. the rotational speed of the bobbin winding up the drawn-off yarn that is taken as guiding value according to which the running-up of the spinning rotor and the fiber feed are controlled, because of the different inertia of such a bobbin.

[0010] It is furthermore useful if the characteristics of the fiber material to be spun or of the yarn being produced are taken into account according to claim 6 for the control of the spinning rotor speed.

[0011] Alternatively, to solve the problem posed, a process according to claim 7 can be applied according to which no driving apparatus for the spinning rotor is provided on the service unit, but whereby the spinning rotor is driven at the required speed in every work phase by means of a change in the transmission ratio between a driving apparatus located in the spinning or workstation and the spinning rotor, said change being controlled in the service unit.

[0012] In an advantageous embodiment of the process according to the invention, the rotor speed is maintained at least substantially constant during piecing, according to claim 8.

[0013] In another advantageous further development of the process according to claim 9, the drive transmission device can be presented to an element directly or indirectly connected to the spinning rotor inorder to drive it and not to the spinning rotor itself.

[0014] A device as in claim 10 is used to carry out the process according to the invention. By assigning a controlled drive transmission device to the spinning rotor the latter can be driven precisely at the low speed desired for the piecing process.

[0015] In an advantageous embodiment of the device according to the invention as in claim 11, the drive transmission device can be associated with a controlled driving apparatus which can be designed as part of the piecing apparatus in an advantageous further development of the device according to the invention as in claim 12.

[0016] The piecing apparatus is provided with an actuating element as in claim 13 in order to actuate the drive transmission device.

[0017] According to the invention and according to claim 14, provisions can be made for the drive transmission device to be connected for drive indirectly to the spinning rotor via one or several interposed elements during the piecing process, instead of being connected directly to the spinning rotor.

[0018] In a preferred embodiment of the object of the invention, a friction wheel is provided according to claim 15 and/or 16, which drives the spinning rotor via an interposed supporting disk that supports the spinning rotor.

[0019] The control device according to claim 17 is advantageously programmable. Here a control connection between the drives of the spinning rotor, of the feed device and of a draw-off device of the pieced yarn can be provided in an advantageous further development of the device according to the invention according to claim 18 and/or 19.

[0020] It is an advantage if a device supplying a reference value for the control of the rotational speed is provided according to claim 20 and/or 21. Furthermore, according to claim 22, a device to influence the evolution of the spinning rotor speed in function of the characteristics of the fiber material to be spun or of the yarn to be produced can be provided.

[0021] The process and the device according to the invention make a precise and simple control of the rotor speed during piecing possible. Reliability during spinning can be increased in this manner, and the resulting piecing joint can be improved.

[0022] Examples of embodiments of the invention are explained below through drawings.

[0023]FIG. 1 shows a device according to the invention of a rotor spinning machine including its control connections in a schematic lateral view and

[0024]FIG. 2 is a schematic representation of the drive ratios pertaining to the spinning rotor during the piecing process, during stoppage and during normal operation.

[0025] In FIG. 1, on the left side of the drawing, a broken line indicates a rotor-spinning machine 1, while a service unit 2 is indicated on the right side of the drawing by means of a dash-dot line.

[0026] Normally a rotor spinning machine 1 has a plurality of identical workstations 10 located side by side, alongside which the earlier-mentioned service unit 2 can be moved, so as to be able to service each one of these workstations 10 when necessary, e.g. in order to exchange a full bobbin 110 against an empty bobbin (not shown) or in order to piece a yearn F following an interruption of production at a workstation 10 and thus to resume the spinning process.

[0027] At each of these workstations 10 installed side by side, an open-end spinning device 2 is provided. It is provided with a spinning rotor 30 as a spinning element, which is provided with a rotor shaft 31 according to the embodiment shown, by means of which it is supported and driven. The spinning rotor 30 is supported in a known manner by its rotor shaft in the nip of supporting disks 32. In addition, normally an axial support is also provided for the spinning rotor 30. This support is not shown and described because it is not needed in order to understand the present invention. This also applies to other normally used elements that are not shown in the figures and neither are described therefore, but it is understood of course that such elements and aggregates are provided in the usual way.

[0028] A drive belt 12 extending along the plurality of workstations 10 drives the spinning rotor 30 at a high rotational speed, the operating speed, during normal production.

[0029] To be able to stop the spinning rotor 30 when necessary, a device 4 is provided which has on the one hand a lifting device 40 to lift the drive belt 12 from the rotor shaft 31, and on the other hand a braking device 41 to stop the spinning rotor 30, which can be brought to bear on the rotor shaft 31. In the embodiment shown, the lifting device 40 and the braking device 41 are linked together by means of a rod system 42 in such manner that when the drive belt 12 is lifted from the rotor shaft 31, the braking device 41 is applied to the latter, and when the braking device 41 releases the rotor shaft 31 the drive belt 12 is again applied on the rotor shaft 31, whereby the rotor shaft 31 is released by the braking device 41 in an intermediate position without application of the drive belt 12 on the rotor shaft.

[0030] The rod system 42 is connected to a drive or actuating device 43 that is connected via a control circuit 172 to a control device 17. The above-mentioned drive stages of the spinning rotor 30 (driven by drive belt 12, released by drive belt 12 and braking device 41 or stopped by the applied braking device 41) can be controlled by this actuating device 43.

[0031] The fibers to be spun (not shown) are presented to the spinning rotor 30 by means of an opener device 13 that detaches these fibers in a known manner from the leading end of a fiber sliver B that is fed to it by means of a feeding device 14. The latter is normally provided with a feed roller 140 driven by means of a drive 141. A feed trough 142 interacts with the feed roller 140 and is subjected in a known manner to the force of a pressure spring or similar device in an elastic manner in order to hold the fiber sliver B elastically between itself and the feed roller 140.

[0032] The drive 141 of the feeding device 14 is connected by means of a control circuit 170 to the previously mentioned control device 17. The latter may be designed e.g. as a central control device for a plurality of workstations 10 or may be assigned merely to one single workstation 10 and be connected to a central control device (not shown) with which other workstations and control devices (not shown) are connected for control.

[0033] The yarn F spun in the spinning rotor 30 from the fibers is drawn off from the spinning rotor 30 through a yarn draw-off pipe 33 by means of a draw-off device 15. The latter is provided with a driven draw-off roller 150 to which a plurality of workstations 10 located next to each other are assigned, as well as with an individual pressure roller 151 mounted on a swiveling lever 152. This swiveling lever 152 is subjected to the force of an elastic element, in the embodiment shown an extension spring 153, in such manner that the pressure roller 151 is pressed elastically against the driven draw-off roller 150 during normal spinning operation.

[0034] In draw-off direction the draw-off device 15 is followed by a yarn tension compensation hoop 16 ensuring that the yarn F fed to the bobbin 110 is essentially under a constant tension, independently of its traversing position.

[0035] The bobbin 110 is located in a winding device 11 and is driven by a winding roller 111 in normal spinning operation. The bobbin 110 is held rotatably between two swiveling bobbin holders 112.

[0036] As mentioned previously, a service unit 2 interacts with the workstations 10 of the rotor-spinning machine 1. It is provided with a piecing apparatus 9 that is provided in the shown embodiment with a driving apparatus 20 of a drive transmission device 7, a lifting device 21 and a lifting device 22 as well as with an auxiliary drive 23 as essential elements.

[0037] The drive transmission device 7 is provided with a drive transmission wheel 200 located at the end of a driven shaft 201 that is capable of displacement in axial direction. The drive transmission wheel 200 is located in the end position indicated by a continuous line within the contours of the service unit 2, so that the latter is able to able to travel unhindered alongside the rotor spinning machine 1. In its other position 200 a indicated by a broken line, the drive transmission wheel 200 is in a common plane E with the supporting disk 32. The driving apparatus 20 is designed so that, in addition to the described displacement, it is able to cause also the rotation of the shaft 201 supporting the drive transmission wheel 200.

[0038] A lifting device 21 with a lifting rod 210 is assigned to the driving apparatus 20 and serves to move the driving apparatus 20 in such manner that the drive transmission wheel 200 can be brought from the position 200 a indicated by the broken line to press against the supporting wheel 32 located in a same plane E as the drive transmission wheel 200 (drive transmission position 200 b).

[0039] The driving apparatus 20 as well as the lifting device 21 is connected to a control device 5 located on the service unit 2 by means of a control circuit 50 or 51.

[0040] A lifting device 22 mounted on the service unit 2 can be presented to the swiveling lever 152 with the pressure roller 151 of the draw-off device 15. This lifting device 22 has a swiveling lever 220 which is mounted according the embodiment shown so as to be capable of swiveling on a piston rod 221 which can in turn be moved in axial direction by a drive 222 (cylinder or similar device). An additional piston rod 223 is connected to a drive 224 and bears a coupling element 225 that is articulatedly connected at its other end to the swiveling lever 220 between its two ends. To be able to control the swiveling lever 220 in the desired manner, the two drives 222 and 224 are connected to the control device 5 by means of control circuits 52 or 53.

[0041] The bobbin 110 can be lifted by means not shown here from the winding roller 111 so that it then assumes the position shown in FIG. 1. In this lifted position of the bobbin 110 it can be assigned an auxiliary drive 23 which is provided with a swiveling arm 230 with an auxiliary drive roller 231 at its free end. The arm 230 is associated with a drive 233 that is connected by means of a control circuit 55 to the control device 5 of the service unit 2.

[0042] The winding device 11 is assigned a monitoring device 6. According to the embodiment shown as an example in FIG. 1, this monitoring device 6 has a rod 60 connected to the arm 230 between its ends, this rod being mounted pivotably on an axis 62 by means of a scanning device 61 provided with a housing. This scanning device 61 has the task to detect the position of the rod 60 relative to itself. The scanning device 61 is connected by means of a control circuit 56 to the control device 5.

[0043] The control device 5 shown here has a receiving bay 57 into which a data carrier, e.g. in form of a CD-ROM, a diskette, etc. can be introduced on which a basic program for the piecing of the yarn F is stored.

[0044] The control device 5 is connected by means of a control circuit 171 to the control device 17 of the rotor-spinning machine 1.

[0045] The normal production of a yarn F takes place in the usual manner. A fiber sliver B is fed by means of the feeding device 14 to the opener device 13 which continuously detaches fibers from the leading end of the fiber sliver B and conveys them to the rotating spinning rotor 30 in which the fibers are deposited in form of a fiber ring. The end of the continuously drawn off yarn F is in contact with this fiber ring and as it is drawn off, constantly integrates the fiber ring. The drawing off of the yarn is caused by the draw-off device 15, in that the pressure roller 151 is held in elastic contact against the driven draw-off roller 150 and thus conveys the yarn F held in the draw-off device. The yarn F is guided over the yarn tension compensation hoop 16 and is traversed by means of a traversing device not shown here as it is wound up on the bobbin 110. During that time the bobbin is pressed against the driven winding roller 111.

[0046] If an interruption of production occurs, be it as a result of an accidental yarn breakage or as a result of a stoppage of the open-end spinning device 3 of an individual workstation 10 or of the entire rotor spinning machine 1 brought about purposely by an operator, this termination or interruption of production takes place in the usual manner. Among other things, at least the drive 141 of the feeding device 14 and the roller 110 are stopped. The roller 110 is stopped in the usual manner, by lifting it from the winding roller 111, and this is therefore not shown.

[0047] When production is to be resumed again, the service unit 2 travels to the workstation 10 to be started up again in order to carry out the piecing process. At that point in time at the latest, the spinning rotor 30 is stopped by means of the device 4 and its rod system 42.

[0048] The drive belt 12 is at the same time lifted from the rotor shaft 31 and the braking device 41 is caused to act on the rotor shaft 31.

[0049] Piecing is controlled by the control device 5 of the piecing apparatus 9 to which the devices and aggregates used during piecing are connected for control.

[0050] In preparation of piecing, the auxiliary drive 23 is first presented to the bobbin 110 which has been lifted off from the winding roller 111. The drive 233 drives the auxiliary drive roller 231 so that the bobbin 110 is rotated in unwinding direction, while a not-shown yarn take-up device searches for the yarn end located at the surface of the bobbin, grasps it and takes it up in accordance with the reverse rotation speed of the bobbin 10. The yarn end is put into an optimal state for piecing in the usual manner (by means which are also not shown here) and is then placed in readiness position in proximity of the spinning rotor 30, whereby the return feeding of the yarn F can be interrupted once or several times in function of the required yarn movements and treatments by stopping the drive 233. During the return feeding of the yarn F into the mentioned readiness position in proximity of the spinning rotor 30, a yarn reserve (not shown) is normally formed which is needed for the subsequent actual piecing. When the yarn F has reached the readiness position the auxiliary drive roller 231 is stopped.

[0051] In synchronization with the return feeding of the yarn end into a readiness position from which the actual piecing takes place at the given point in time, the pressure roller 151 of the draw-off device 15 is lifted from the draw-off roller 150 which continues to be driven as before. For this purpose the piston rod 221 is pushed in the direction of the rotor-spinning machine 1 by means of the drive 222. The drive 224 is not yet actuated. In this manner and during the advance of the piston rod 221, the swiveling lever 220 which is articulatedly mounted at the end of this piston rod 221 is swiveled up by the piston rod 223 which remains behind and by the coupling link 225, SO that upon completion of this advance movement the grasper 226 is located above the free end of the swiveling lever 152 supporting the pressure roller 151. By actuating the drive 224 the swiveling lever 220 is now lowered and seizes the swiveling lever 152 with the pressure roller 151.

[0052] Simultaneous withdrawal of the piston rods 221 and 223 by means of their drives 222 and 224 causes the swiveling lever 152 to be pulled away from the draw-off roller 150 so that the pressure roller 151 also moves away from the latter.

[0053] For piecing it is necessary that the spinning rotor 30 rotates at a very defined rotational speed with which the start of fiber feeding into the spinning rotor 30 and the quantity of the fibers to be fed, the return delivery of the yarn end in the readiness position into the rotating spinning rotor as well as the drawing off of the yarn F must be synchronized.

[0054] To be able to drive the spinning rotor 30 at the desired rotational speed, the control device 5 of the piecing apparatus 9 actuates the driving apparatus 20 and the shaft 201 bearing the drive transmission wheel 200 is moved from the starting or rest position indicated by a continuous line out of the service unit 2 in the direction of the rotor spinning machine 1 so far that the drive transmission wheel 200 reaches its position 200 a in which it is in one and the same plane E with the supporting disk 32.

[0055] By actuating the lifting device 21, the driving apparatus 20 is now moved with the drive transmission wheel 200 at the end of shaft 201 in such manner that the drive transmission wheel 200 reaches its drive transmission position 200 b and is thereby pressed against the circumference of the supporting disk 32. At the latest at this point in time, the driving apparatus 20 which, in addition to the axial displacement of the shaft 201 also causes the driven rotation of this shaft 201 and thereby of the drive transmission wheel 200, is actuated in such manner that the drive transmission wheel 200 is caused to rotate in a controlled manner and thereby causes also the rotor shaft 31 and thereby the spinning rotor 20 to rotate via the intercalated supporting disk 32. The rotation caused by the control device 5 by means of the driving apparatus 20 is controlled in such manner in that case that the spinning rotor 30 is brought to its rotational speed selected for piecing.

[0056] The rotational speed of the spinning rotor 30 can be kept constant during the subsequent piecing process or can be driven in a controlled manner with minimal acceleration so that the piecing process described below is carried out within a rotational speed range of the spinning rotor 30 that is predetermined by the control device 5.

[0057] The operational steps described above have prepared the actual piecing that can now be carried out. First, the drive 141 of the feeding device 14 resumes operation so that fibers reach the interior of the rotating spinning rotor 30 and are deposited therein in form of a forming fiber ring. The yarn end is then fed back into the spinning rotor 30 by releasing the previously formed yarn reserve until it is in contact with the accumulated fibers therein.

[0058] In synchronization with the resumption of fiber feed or conveying into the spinning rotor 30 and the return feeding of the yarn into the spinning rotor 30, the drawing-off of the yarn F from the spinning rotor 30 is resumed. For this purpose the drive 233 of the auxiliary drive roller 231 is actuated by the control device 5 of the piecing apparatus 9 in such manner that the bobbin 110 is driven in winding direction. The winding speed is increased for this in accordance with a predetermined program in form of an acceleration curve until it reaches the full operating speed of the bobbin 110. Since the pressure roller 151 is lifted off from the draw-off roller 150, the bobbin 110 becomes the draw-off device for the spun yarn F during the piecing draw-off.

[0059] During this run-up of the bobbin 110 the rotational speeds of the spinning rotor 30 and of the feed roller 140 are increased so that the rotational speed of the spinning rotor 30 and of the feed roller 140 and of the bobbin 110 are coordinated with each other until the operating speed is reached, and remain thus coordinated, but this does not necessarily mean that the speed ratios among these rotational speeds must remain unchanged during the entire time. Since the centrifugal force in the spinning rotor 30 increases during its run-up and accordingly increasingly hinders the propagation of the rotation from the yarn draw-off pipe 33 in which the rotation of the yarn F originates to the point at which the yarn end incorporates the fibers in the spinning rotor 30 in form of a deposited fiber ring, it may be advantageous to change this speed ratio in function of the rotor speed in order to obtain a uniform yarn quality.

[0060] The acceleration of the bobbin 110 can however not be controlled as desired since its acceleration depends on its mass. The larger the bobbin 110 is, the greater is also the mass to be driven and to be accelerated by the auxiliary drive roller 231. For this reason the bobbin 110 cannot be accelerated e.g. in function of the acceleration of the feed roller 140, since the feed roller 140 has a very small mass and can therefore reach its operating speed very rapidly. For this reason a scanning device 61 is provided in the shown embodiment to determine the diameter of the bobbin 110 driven by the auxiliary roller 231. The smaller the mass of the bobbin 110, the smaller is also its diameter, so that the diameter can be used as a reference value for the mass of the bobbin 110. The smaller the diameter of the bobbin 110, the lower does the arm 230 with the auxiliary drive 231 descend in the direction of the winding roller 111, so that the swiveling path of the arm 230 has a fixed ratio to the bobbin diameter and thus also to the mass of the bobbin 110.

[0061] The swiveling path of the arm 230 is ascertained by means of the scanning device 61 across from which the rod 60 articulatedly connected to the arm 230 can be displaced in axial direction in direct function of the bobbin diameter. The scanning device 61 reports the extent of displacement or the relative position of the rod 60 relative to the scanning device 61 to the control device 5 which converts this information into control signals to control the rotational speed of the driving apparatus 20 to drive the spinning rotor 30, of the drive 233 of the auxiliary drive 23 of the bobbin 110 and of the drive 141 of the feeding device 14. If the scanning device 61 reports a large bobbin diameter to the control device 5, the control device 5 causes the acceleration of the spinning rotor 30 by means of the driving apparatus 20 to be slower than in case of a small diameter of the bobbin 110. The drive 141 of the feeding device 14 and the drive 233 of the auxiliary drive 23 of the bobbin 110 are then driven correspondingly.

[0062] It goes without saying that the accelerations of the spinning rotor 30, of the bobbin 110 and of the feeding device 14 have a predetermined speed ratio relative to each other which can also change during the acceleration in accordance with a predetermined program, and that these speeds are only accelerated sufficiently so that the bobbin 110 is reliably able to follow the acceleration dictated by the drive 233.

[0063] The reference value for the rotor speed need however not necessarily be supplied by the bobbin 110; it may also be advantageous to control the acceleration of the bobbin 110 and of the spinning rotor 30 in function of a controlled acceleration of the feed roller 140. Since the leading end of the fiber sliver B reaches the full thickness of the fiber sliver B very rapidly, even when this end has been prepared especially for the piecing process, the feed roller 140 must be driven and accelerated very slowly in order to achieve acceptable results for the piecing joint, i.e. the point between the end of the return-fed yarn F and the beginning of the newly spun yarn F.

[0064] The evolution of the rotational speed of the spinning rotor 30 is controlled according to a predetermined program for the entire time during which its speed deviates from its operating speed.

[0065] In the period of time until the start of the piecing process, the evolution of the speed of the spinning rotor 30 does not play a significant role, so that in accelerating it one must only ensure that the period between the moment when the spinning rotor is first driven by the driving apparatus 20 and the actual piecing process, e.g. when a contact is established between the yarn F fed back into the spinning rotor 30 and the fibers deposited therein in form of a fiber ring, is sufficiently long to bring the spinning rotor 30 up to its piecing speed during that period. Thus it is possible, for instance, to bring the spinning rotor 30 in this case with high, uncontrolled acceleration to its piecing speed.

[0066] The acceleration of the spinning rotor 30 following piecing follows the program stored in the control device 5. Here either the acceleration of the spinning rotor 30 (and of its feed roller 140) can be effected in different ways in function of the size and mass of the bobbin 110 monitored by the monitoring device 6, or the acceleration of the bobbin 110, of the feed roller 140 and of the spinning rotor 30 is kept so minimal that the bobbin 110 can reliably follow the rotational speed course set for it by the auxiliary drive roller 231.

[0067] It is not absolutely required to use any one of the rotational speeds important during piecing and subsequent acceleration as a reference value for the other rotational speeds. Alternatively, all rotational speed courses of spinning rotor 30, bobbin 110 and feeding device 14 can be set directly by the control device 5.

[0068] When the spinning rotor 30, the feed roller 140 and the bobbin 110 have reached their respective operating speeds, the normal operating conditions are re-established. The driving of the bobbin 110 and of the spinning rotor 30 effected until then by the service unit 2 can therefore be normalized again and be given back to the rotor spinning machine 1 itself, the driving of the feeding device 14 however, already controlled until then by the control device 17 of the workstation 10 need not be switched over.

[0069] When it has reached its operating speed, the bobbin 110 is lowered on the winding roller 111 so that the latter takes over the driving of the bobbin 110 from then on, and the auxiliary drive roller 231 is lifted off from the bobbin 110. Furthermore, by appropriate control of the drives 222 and 224, the swiveling lever 152 is released by the grasper 226 so that the swiveling lever 152 now brings the pressure roller 151 to bear upon the draw-off roller 150 under the action of the extension spring 153 and the yarn F is drawn off by the draw-off device 15 from the spinning rotor 30.

[0070] By actuating the actuating device 43 the rotor shaft 31 is released by the braking device 41 and at the same time the drive belt 12 is brought to bear on the rotor shaft 31. Furthermore the actuation of the lifting device 21 causes the drive transmission wheel 200 to be lifted from the supporting disk 32, whereupon the drive device 20 stops the drive transmission wheel 200 of the drive transmission device 7 and causes the withdrawal of the latter to within the contours of the service unit 2.

[0071] When the service unit 2 no longer intervenes with any of the elements of the workstation 10 or no longer interacts with one of them, the service unit 2 leaves this workstation 10 to resume its task at another workstation 10.

[0072]FIG. 1 merely shows an example of an embodiment. Under the present invention a number of variants of the shown device as well as of the described process are however possible, e.g. by exchanging individual characteristics against equivalents or by other combinations of these characteristics or of their equivalents. Thus the drive transmission wheel 200 in the shown embodiment is presented to the supporting disk 32 by a movement within the plane E. Such a movement of the drive transmission wheel 200 is however not a requirement to carry out the described process. Alternatively it is also possible to present the drive transmission wheel 200 not to the supporting disk 32 but to the rotor shaft 31 through a movement that is radial relative to the rotor shaft 31. Depending on the design of the open-end spinning device 3 or of the workstation 10, this movement can deviate in this case from the shown embodiment where this presentation movement takes place from below to above and take place in another presentation direction within the plane E.

[0073] In principle the drive transmission wheel 200 can be put in drive connection with any element that has a fixed rotational speed ratio to the rotational speed of the spinning rotor 30, in order to drive the spinning rotor 30 during the time when its speed deviates from its operating speed. As shown so far, this element can be constituted by one of the supporting disks 32 supporting the rotor shaft 31 (or the spinning rotor 30 itself, in a manner not shown). When such supporting disks 32 are provided for the direct or indirect support of the spinning rotor 30, such a drive has the additional advantage that the drive transmission wheel 200 need be driven only at a relatively low speed by the driving apparatus 20 of the service unit 2 in view of the transmission ratio between supporting disk 32 and rotor shaft 31 or spinning rotor 30.

[0074] As indicated earlier, the drive transmission wheel 200 can be brought into contact with the circumference of the spinning rotor 30 to be driven, especially when the spinning rotor 30 is supported directly (not shown) without using a rotor shaft 31 and/or supporting disks 32. The drive of the spinning rotor 30 can also be driven during normal production in some other, known manner, also without tangential belt 12 and thereby in deviation from the drawing in FIG. 1.

[0075] In another alternative embodiment the driving apparatus 20 can be located in a swiveling housing (not shown) and by being swiveled out of range of the service unit 2 together with the drive transmission device 7 constituted by the drive transmission wheel 200, can be brought into contact with the rotor shaft 31 or with another element in drive connection with the rotor shaft 31, e.g. the supporting disk 32, so that the direction of movement falls as a tangent into this plane E only in proximity of the drive transmission position 200 b of the drive transmission wheel 200.

[0076] Furthermore and in accordance with another variant that is not shown, the drive transmission wheel 200 can be located at least in its drive position in a plane (not shown) that intersects the shown plane E at essentially a right angle. In this case the drive transmission wheel 200 that assumes its drive transmission position 200 b is pressed against a face of the supporting disk 32. Here too the drive transmission wheel 200 can be presented to the element to be driven, e.g. rotor shaft 31, supporting disk 32 etc., in different manners, e.g. in form of a linear or circular movement. Presentation paths of different design are also possible, e.g. in that an element supporting the shaft 201 of the drive transmission wheel 200 moves in a guide in which it slides (not shown).

[0077] If the drive transmission wheel 200 and the element with which the drive transmission wheel 200 can be connected for drive is given an appropriate form, the drive transmission wheel 200 must be brought into contact with the supporting disk 32, etc., neither in a common plane E shared with supporting disk 32 etc., nor in a plane intersecting this plane E at a right angle, but it is entirely possible to connect the drive transmission wheel 200 into drive connection with the element to be driven (supporting disk 32, spinning rotor 30, rotor shaft 31) at any desired angle.

[0078] The drive transmission wheel 200 can also be designed in a great variety of ways; thus a friction wheel, a toothed wheel (e.g. in form of a pinion gear) etc. can be used and be given a different form, e.g. that of a conical gear wheel, etc.

[0079] In deviation from the shown embodiment it is also not required that the spinning rotor 30 be separated from the drive belt 12 by means of a rod system 42 bearing a lifting device 40 and a braking device 41 of the type shown. It is perfectly possible to design the lifting device 40 and the braking device 41 independently of each other and e.g. to drive them with their own drives (solenoid, hydraulic or pneumatic cylinder etc.), whereby these two not shown drives are connected for control to the control device 17.

[0080] In a variant of the shown device the actuating device 43 need not be connected via a control circuit 172 to the control device 17 and via the latter to the control device 5. Instead, the rod system 42 can be connected to a cover of the open-end spinning device 3 which can be opened and closed again in a manner not shown here by a not-shown device connected to the control device 5 of the piecing apparatus 9 installed on the service unit 2, whereby the different drive states of the spinning rotor (driven by drive belt 12, released by drive belt 12 and braking device 41 as well as stopped by the applied braking device 41) are controlled in function of the swivel position of the not-shown cover.

[0081] In addition to the receiving bay 57 for a suitable data support, the shown control device 5 is provided with two additional input devices 570 and 571 by means of which it is possible to intervene in the basic program supplied by the data support. The input device 570 for example, is a device for the input of the fiber characteristics pertaining to material, fiber length, curling characteristics, etc. By means of this input device 570 and the program stored in the control device 5 it is thus possible to change the piecing conditions accordingly, so that optimal piecing conditions with respect to fiber incorporation can be achieved at all times. In an analogous manner, the desired yarn characteristics with respect to twist, yarn thickness, etc. can be adjusted by means of the second input device 571. The piecing process and in particular also the evolution of the rotational speed of the spinning rotor 30 are influenced here in this manner by means of the two input devices 570 and 571. The constant piecing speed of the spinning rotor 30, e.g. the speed range of the spinning rotor 30 provided for piecing, can be adjusted here in function of the setting selected by the input devices 570 and/or 571.

[0082] It is of course also possible to enter the inputs also by means of a combined input device (not shown) into the control device 5.

[0083] The embodiment of the control device 5 shown and described here with respect to programming and influencing the stored program is merely one possible embodiment example selected to explain the process and the device; other embodiments of the control device 5, especially also with a view to controlling the evolution of the rotational speed of the spinning rotor 30, are entirely possible. In some cases the control of the evolution of the rotational speed of the spinning rotor 30 is so precise that it is possible to do without an adjusting or programming possibility to take into account the characteristics of the fiber material and of the yarn F to be produced.

[0084] Nor is it necessary to provide for a course of the piecing process in the manner described above; other piecing courses where piecing takes place at a rotational speed of the spinning rotor 30 that is lower than its operating speed can be used, whereby the spinning rotor 30 is driven during the piecing process in the described manner by the driving apparatus 20 of the service unit 2 by means of the drive transmission device 7.

[0085] In the time during which the spinning rotor 30 is under the control of the service unit and of its driving apparatus 20, it is advantageous to suppress the direct drive of the spinning rotor 30 by the drive belt 12. This is effected in a known manner by lifting the drive belt 12 off from the rotor shaft 31, as was described earlier by e.g. using the actuating device 43 and the rod system 42. For this purpose the control device 5 transmits an appropriate signal via the control circuit 171 to the control device 17, which in turn controls the actuating device 43 via control circuit 172.

[0086] In the examples of embodiments described above, the driving apparatus 20 of the spinning rotor 30 is located on the service unit 2 traveling alongside the workstations 10. At variance with this, an embodiment of a drive transmission device 70 is described below that dispenses with a dedicated, i.e. additional driving apparatus 20 of the spinning rotor 30. The drive transmission device 70 rather causes the drive belt 12 or another driving device provided in the rotor spinning machine 1 itself to be brought to bear on the spinning rotor 30 with different transmission ratios, depending on the work phase.

[0087] The drive transmission device 70 has as its essential element a holder 8 (indicated only schematically in FIG. 2) that holds a belt application roller 80, normally used in rotor spinning devices, and at a distance of same, on the other side of the drive belt 12, a stepped roller 81 with a first zone 810 having a large diameter D and with a second zone 811 having a smaller diameter d. The zone 810 of the stepped roller 81 with the large diameter D presses against the drive belt 12, at least during the time when the stepped roller 81 is to transmit the rotation received from the drive belt 12, while its zone 811 with the small diameter d presses against one of the supporting disks 32.

[0088] According to FIG. 2, the holder 8 is mounted by means of two stationary guides 87 and 88 provided in the workstation 10 so as to be capable of axial movement. It has an actuating stop 82 at a suitable location against which an actuating element 71 can be brought to bear. This actuating element 71 which is shown only schematically is controlled by the control device 5 of the service unit 2, similarly to that which was described earlier in connection with the drive wheel 200, but with the difference that the driving apparatus 20 does not impart any rotational drive and that the actuating element 71 is not presented to a supporting disk 32 but to the drive transmission device 70.

[0089] The actuating element 71 as the task of moving the drive transmission device 70 from a rest position in which it is non-operational into a transmission position in which it connects the drive belt 12 (or some other driving device provided in the rotor spinning machine 21) to the spinning rotor 30 to drive it.

[0090] The holder 8 is furthermore provided with a stop arm 83 which is in contact with a stationary stop 870 in its normal operating position, said stop 870 consisting according to the embodiment shown in FIG. 2 of a face of the guide 87. The holder 8 is furthermore provided with an arm 84 in which the end of the extension spring 86 is anchored, its other end being anchored in a stationary spring hook 880, e.g. supported by the guide 88.

[0091] The holder 8 has yet another actuating stop 85 to which a stopping lever 44 can be advanced. This stopping lever 44 is part of the device 4 described above through FIG. 1 and suitably adapted to it, and is connected to the actuating device 43 (see FIG. 1) and is brought by the control device 17 to act upon the holder 8 when the open-end spinning device is stopped on purpose or accidentally (e.g. in case of yarn breakage).

[0092] The holder 8 constitutes the previously mentioned drive transmission device 70 whose three work positions are indicated in FIG. 2 by continuous, dash-dot or broken lines.

[0093] The change of position of the drive transmission device 70 for piecing is effected by means of the above-mentioned actuating element 71 that is controlled by the service unit 2 in a manner not shown, in order to take the holder 8 and thereby also the drive transmission device 70 into our out of operation.

[0094] During the normal, undisturbed spinning operation the drive transmission device 70 is presented to the spinning rotor 30 (or to an element connected to it to drive it, in the embodiment shown with a supporting disk 32). Thereby the actuating element 71 as well as the stopping lever 44 releases the holder 8, which thus, as a result of the action of the extension spring 86, together with the belt pressing roller 80 and the stepped roller 81 assumes the position indicated in FIG. 2 by a continuous line in which the stop arm 83 is pressed against the stationary stop 870. The stepped roller 81 is pressed in this case with its zone 810 having the larger diameter D against the drive belt 12, while its zone 811 with the smaller diameter d is pressed against the supporting disk 32. Since the rotor shaft 31 is located in the nip between two supporting disks 32 or supporting disk pair, it (and through it the spinning rotor 30) is thus driven by the drive belt 12 located at the workstation 10 (i.e. extending through the workstation 10) via the stepped roller 81 and the supporting disk 32. Due to the transmission ratio resulting from the different diameters D and d of the zones 810 and 811 of the stepped roller 81 and between the zone 811 of the stepped roller 81 and the supporting disk 32, the spinning rotor 30 is driven at a speed that is substantially greater than if the rotor shaft 31 were driven directly by the drive belt 12.

[0095] Although not shown separately, it goes without saying that known means are provided to secure the rotor shaft 31 in the nip of the supporting disks 32. The rotor shaft 31 can be born here in principle in the usual manner by means of one or two pairs of supporting disks 32, whereby the supporting disks of a pair of supporting disks can be located in a known manner in a joint plane (see FIG. 1) or in a parallel plane (see FIG. 2) and if necessary with partial overlap.

[0096] In case of stoppage of the open-end spinning device 3, the holder 8 assumes an intermediate position (indicated by dashes and dots in FIG. 2) in which the stepped roller 81 is lifted from the supporting disk 32 while the drive belt 12 has however not come into contact with the rotor shaft 31 (see position 12′). For this the control device 17 and the actuating device 43 activate the cited stopping lever 44 as required.

[0097] If the open-end spinning device 3 is to be taken into operation again after a stoppage of the workstation 10 and of its aggregate, the actuating element 71 is first presented to the actuating stop 82 under the control emanating from the service unit 2 that has been called up in the meantime in a known manner, and the holder 8 is moved against the action of the extension spring 86 in such manner that the stepped roller 81 is removed even further from the drive belt 12 and also from the supporting disk 32 (see broken line drawn in FIG. 2). In this manner the drive transmission device 7 continues to be kept out of action while the belt pressing roller 80 is pressed against the drive belt 12 (position″) and presses it against the rotor shaft 31, so that the spinning rotor 30 is now driven directly by the drive belt 12. In this position of the holder 8, the stepped roller 81 is disengaged from the drive belt 12 as well as from the supporting disk 32. Since the transmission between drive belt and rotor shaft 31 does not take place when the rotor is driven in this manner, the rotational piecing speed of the spinning rotor 30 is considerably slower than with the indirect drive via the stepped roller 81 and the supporting disk 32. In this piecing position of the drive transmission device 70, in which the spinning rotor 30 is driven in a defined manner at a constant rotational speed that is lower than its operating speed, the piecing process is now carried out in the known manner.

[0098] When the piecing process has been completed successfully, the actuating element 71 and, if this has not already occurred during the piecing process, the stopping lever 44 is pulled back now at the latest, so that the holder 8 is released and, due to the action upon it of the extension spring 86, follows this movement until its stop arm 83 comes into contact with the stop 870. Thereby the drive belt 12 is disengaged from the rotor shaft 31 while the drive transmission device 70 transmits the movement of the drive belt 12 via the stepped roller 81 and the supporting disk 32 to the rotor shaft 31 and thereby also to the spinning rotor 30. The driven elements of the drive transmission device 70 (stepped roller 81) are thus driven in such manner that the spinning rotor 30 runs up rapidly to its operating speed, and then remains at this operating speed. The normal drive conditions for production are re-established.

[0099] When all the elements intervening in the open-end spinning device 3 during the piecing phase have again been pulled back into the confines of the service unit 2, the latter can again leave the workstation 10 in order to carry out necessary service tasks at another workstation 10.

[0100] In the embodiment described above, the rotational speed of the spinning rotor 30 is set in a fixed manner by the relationship between production speed and piecing speed of the spinning rotor 30. The relationship can be changed if necessary by replacing the stepped roller 81 by one with a different diameter ratio of the zones 810 and 811 and thus adapted to the desired conditions.

[0101] A continuous adaptation is also possible, e.g. by designing the drive transfer from the stepped roller 81 to the supporting disk 32 or of an intermediate disk (not shown) interacting with the supporting disk 32 in form of a conical gear or similar device that can be adjusted in function of current conditions to the desired speed ratio.

[0102] If the drive transmission device 70 by means of which the drive is taken away from a driving device 12 of the workstation 10 and is transferred to the spinning rotor 30 is active merely while the piecing and service phase, it can also be installed on the service unit 2 as an alternative and be presented to the open-end spinning device 3 only when needed. The transmission ratios must be selected in the latter case so that the spinning rotor 30 is driven in the desired manner at reduced speed when the drive transmission device 70 is active. In such case the spinning rotor is driven during normal production independently of the drive transmission device 70, contrary to the embodiment described above through FIG. 2.

[0103] Whether or not the drive transmission device 7 or 70 is active during the time when the spinning rotor 30 is rotating at its operating speed or during the time when the spinning rotor 30 rotates only at a reduced speed, its piecing speed, the change from one of these speeds to the other is always caused by intervention of the service unit 2 in the driving of the spinning rotor 30, whereby the drive transmission device can obtain its driving action from the service unit 2 (drive transmission device 7 in FIG. 1) or from a driving device (drive belt 12) of the rotor spinning machine 1 itself (drive transmission device 70 in FIG. 2). 

1. Process for the production of a yarn in an open-end spinning device in which a spinning rotor is slowed down to a low piecing speed for piecing and the yarn is produced after piecing at a production speed of the spinning rotor that is higher han the piecing speed, whereby the rotor speed is influenced by the controls of a service unit traveling alongside a plurality of identical spinning stations and the yarn is pieced at this low piecing speed as fibers are fed to it and is then drawn off from the spinning rotor while the spinning rotor runs up to its operating speed, characterized in that a drive transmission device is presented by the service unit to the spinning rotor and this drive transmission device is driven in such manner that the spinning rotor rotates at a piecing speed that is lower than the operating speed, in that the piecing process is then carried out and the drive transmission device is taken out of action and the spinning rotor is driven at its operating speed.
 2. Process as in claim 1, characterized in that the drive transmission device is driven by a driving apparatus located on the service unit according to a predetermined rotational speed course.
 3. Process as in claim 1 or 2, characterized in that the rotational speed of the spinning rotor is increased in a controlled manner during piecing.
 4. Process as in claim 3, characterized in that the acceleration of the spinning rotor after completed piecing from the piecing speed until it reaches its operating speed is controlled in coordination with the fiber feed to the open-end spinning device and/or with the drawing off of the yarn from the open-end spinning device.
 5. Process as in claim 3, characterized in that the evolution of the rotational speed is controlled in function of the acceleration behavior of a bobbin winding up the yarn.
 6. Process as in claim 3, characterized in that the evolution of the rotor speed is controlled in function of the material to be spun and/or of the desired characteristics of the yarn to be produced.
 7. Process for the production of a yarn in an open-end spinning device in which a spinning rotor is slowed down to a low piecing speed for piecing and the yarn is produced after piecing at an operating speed that is higher than the piecing speed, whereby the rotor speed is influenced by control from a service unit traveling alongside a plurality of identical spinning stations and the yarn is pieced while being fed fibers at this low piecing speed and is then drawn off from the spinning rotor while the spinning rotor runs up to its operating speed, characterized in that a drive transmission device presented to the spinning rotor by the service unit is taken out of action and the spinning rotor is connected to a driving apparatus located in the spinning station to be driven, by which it is driven at a piecing speed that is lower than the operating speed, in that the piecing process is then carried out and the drive transmission device is again presented to the spinning rotor following the completion of the piecing process, and is driven in such manner that the spinning rotor is brought to its operating speed and is then driven at that operating speed.
 8. Process as in one or several of the claims 1 to 8 and 8 or as in claim 7 or 8, characterized in that the rotational speed of the spinning rotors is kept essentially constant at a piecing speed during piecing.
 9. Process as in one or several of the claims 1 to 6 and 8 or claim 7 or 8, characterized in that the drive transmission device is presented to an element connected to the spinning rotor for driving action instead of to the spinning rotor.
 10. Device for the production of a yarn in an open-end spinning device with a rotatably supported spinning rotor, with a service unit traveling alongside a plurality of identical open-end spinning devices which is provided with a piecing apparatus as well as with a control device to influence the piecing speed of the spinning rotor which is reduced from a predetermined operating speed, for the implementation of the process as in one or several of the claims 1 to 9, characterized in that a drive transmission device (7, 70) is connected to the control device 5 and can be brought by the service unit 2 into engagement with the spinning rotor 30 in order to drive it.
 11. Device as in claim 10, characterized in that the drive transmission device 70 is assigned a driving apparatus 20 controlled by the control device
 5. 12. Device as in claim 11, characterized in that the driving apparatus 20 assigned to the drive transmission device 70 is made in form of a part of the piecing apparatus 9 mounted on the service unit
 2. 13. Device as in claim 10 or 11, characterized in that the piecing apparatus 9 is provided with an actuating element 71 that can be presented to the drive transmission device 70 in order to take it from a rest position into a transfer position in which it transfers the drive from a driving apparatus 12 that is independent of the service unit 2 to the spinning rotor
 30. 14. Device as in one or several of the claims 10 to 13, characterized in that the drive transmission device 7, 70, instead of being connected to the spinning rotor 30 to drive it, can be brought into drive engagement with a drive or supporting element 32 that is in drive connection with the spinning rotor.
 15. Device as in claim 14, in which the spinning rotor is supported by means of a rotor shaft in the nip of supporting disks, characterized in that the drive transmission device 7, 7 0 has a drive transmission wheel 200 that can be brought into engagement with one of the supporting disks
 32. 16. Device as in claim 15, characterized in that the drive transmission wheel 200 can be pressed with its outer circumference against the outer circumference of the supporting disk
 32. 17. Device as in one or several of the claims 10 to 16, characterized in that the control device 5 can be programmed so that the spinning rotor 30 can be driven during piecing at a constant piecing speed adapted to predetermined spinning conditions.
 18. Device as in claim 17, characterized in that the control device 5 is in drive connection with the drives of a feeding device 14 feeding fibers to the open-end spinning device 3 and/or of a draw-off device 110 for the spun yarn F to control the acceleration of the spinning rotor
 30. 19. Device as in claim 17, characterized in that the control device 5 can be programmed in such manner that the spinning rotor 30 can be driven with great acceleration until it reaches the predetermined piecing speed, while it can be accelerated upon completed piecing from the piecing speed until it reaches the operating speed in adaptation to the acceleration of the feeding device 14 and/or of the draw-off device
 110. 20. Device as in one or several of the claims 10 to 19, characterized in that the control device 5 is in drive connection with a device 110, 14 supplying a reference value for the rotor speed.
 21. Device as in claim 20, characterized in that the device supplying the reference value is constituted by a bobbin 110 to which a device 61 for the ascertainment of its fullness is assigned, which is connected for control to the control device
 5. 22. Device as in one or several of the claims 10 to 21, characterized in that the evolution of the rotational speeds of the spinning rotor 30 can be programmed by means of the control device 5 in function of the material to be spun and/or of the desired characteristics of the yearn F to be produced. 